Let's try to solve the problem.
"A well-known watchmaker was robbed. According to him, at 10:00 PM, the lights in his office were turned off at the switchboard in the hallway. He left his office, was hit on the head, and lay unconscious for two hours. Upon awakening, he immediately turned on the light and called the police. However, it was immediately clear to the detective that the whole story was a lie. How did he figure this out?"
Let's take a closer look at the watchmaker's office. You'll notice that all the clocks show the same time. But you'll also notice that a wire runs from the white clock along the wall. Therefore, this clock is powered by electricity.
If the lights went out at 10:00 PM, then the white clock should have stopped at that time. After the lights were turned back on, this clock should be two hours slower than the others. It was this discrepancy that helped the detective.
